*Another tip is to stay in the sun. The data on sun exposure has largely reversed over the last decade; sun exposure is positively correlated with improved health outcomes, but should be done in moderation as to prevent skin issues.
[1] https://www.webmd.com/a-to-z-guides/ss/slideshow-sunlight-he...
> In general, scientists think 5 to 15 minutes -- up to 30 if you’re dark-skinned -- is about right to get the most out of it without causing any health problems.
To me, it seems almost entirely explained by culture.